Contour Curve Research Articles

Clothing Style Recognition Method Based on Digital Image Processing

The use of digital image processing technology to identify clothing styles from clothing images has broad application potential in clothing consumption analysis, auxiliary clothing design and identity recognition. In the current clothing style recognition field for feature extraction and classification of clothing contours, the main methods are extreme learning machine classification based on wavelet Fourier descriptor, and Euclidean distance classification based on fusion features. However, these methods also have some shortcomings. Currently, there is still no effective method to extract features and classify clothing contours. In order to solve this problem, this paper is based on the SVM classification method of Fourier contour description features. The contour curvature characteristic point in the figure can be described as the bending characteristic of the clothing contour curve, and its calculation is simple and intuitive, which improves the judgment effect of the similarity performance of the Hausdorff distance. This paper constructs a multi-resolution framework of the new image, uses edge detection algorithms to obtain the edges of each level of resolution image, and expands them into narrow edge bands, and combines the point distribution model with the edge narrow bands obtained by edge detection to perform multi-resolution image ASM search for. This paper proposes an image fusion algorithm based on algebraic multigrid and adaptive block. Because the coarse grid extracted by the algebraic multi-grid method can extract the detailed information of the image to a certain extent, the original image can be reconstructed from the grid data. Experimental research shows that from the overall recognition rate of various clothing styles, the Fourier descriptor has a high recognition rate for each clothing, and the stability of multiple experiments is also good.

Bionic design and performance test of maize grain cleaning screen through earthworm motion characteristics

The maize mixture feeding with a large mass cannot be migrated backward rapidly along the planar reciprocating vibrating screen, and it is easy to accumulate in the front of the screen, which leads to the decrease of screening efficiency. Based on the reverse engineering technology, using the wavy geometry formed during the earthworm (Pheretima guillelmi) moving as a bionic prototype, a bionic screen was designed to make the maize mixture migrate backward rapidly in the front of the screen. The contour curve of earthworm’s head in an axial contracted state was extracted and fitted to obtain its equation. Based on the difference of concave position of the lower surface’s wavy geometry during the earthworm moving, the motion of the bionic screen was divided into four postures, and the conversion between different postures of the bionic screen was realized by the cam drive mechanism. The kinematics simulation of the bionic screen was carried out through ADAMS, and the displacement and velocity of the bionic screen were analyzed. When the feeding mass of the maize mixture was set at 5 kg/s, 6 kg/s and 7 kg/s, the test results showed that the time of the maize mixture migrated (TOMMM) in the front of the bionic screen was shortened by 0.18 s, 0.71 s, and 1.36 s, respectively, compared with that of planar reciprocating vibrating screen. The total screening time (TST) of the bionic screen was shortened by 1.28 s, 1.33 s, and 1.53 s, respectively. The ability of the maize mixture to be migrated backward was improved. This study can provide a reference for the innovative design of the cleaning screen. Keywords: cleaning screen, maize grain harvester, material accumulation, earthworm, bionic design, motion characteristics DOI: 10.25165/j.ijabe.20211403.6534 Citation: Wang L J, Yu Y T, Zhang S, Feng X, Song L L. Bionic design and performance test of maize grain cleaning screen through earthworm motion characteristics. Int J Agric & Biol Eng, 2021; 14(3): 12–21.

The role of semantics in the perceptual organization of shape

Establishing correspondence between objects is fundamental for object constancy, similarity perception and identifying transformations. Previous studies measured point-to-point correspondence between objects before and after rigid and non-rigid shape transformations. However, we can also identify ‘similar parts’ on extremely different objects, such as butterflies and owls or lizards and whales. We measured point-to-point correspondence between such object pairs. In each trial, a dot was placed on the contour of one object, and participants had to place a dot on ‘the corresponding location’ of the other object. Responses show correspondence is established based on similarities between semantic parts (such as head, wings, or legs). We then measured correspondence between ambiguous objects with different labels (e.g., between ‘duck’ and ‘rabbit’ interpretations of the classic ambiguous figure). Despite identical geometries, correspondences were different across the interpretations, based on semantics (e.g., matching ‘Head’ to ‘Head’, ‘Tail’ to ‘Tail’). We present a zero-parameter model based on labeled semantic part data (obtained from a different group of participants) that well explains our data and outperforms an alternative model based on contour curvature. This demonstrates how we establish correspondence between very different objects by evaluating similarity between semantic parts, combining perceptual organization and cognitive processes.

Analytic Estimation of Three-dimensional Variables for SOC in Iron Phosphate Lithium-ion Battery

A three-dimensional variable analysis method for the estimation of state of charge (SOC) in iron phosphate lithium-ion battery is proposed. The 100Ah/3.6V iron phosphate lithium-ion battery is regarded as the research object. The relationship between SOC and single factor was got by using the control variable method, and the specific expression was got by using the way of data fitting. Then the situation when multiple factors work together is analyzed, and the function between SOC and the three factors—temperature(T),charging voltage(U) and charging current(I) was got by using the way of data fitting. The feasibility of this method is tested with experimental data, and the error analysis has been done. The results indicate that the SOC estimation error of this method is less than 2%. The two-dimensional surface and contour curve is given when charging voltage(U) is 3.3V and under the condition of different charging current and temperature.

Synergistic modification of the tribological properties of polytetrafluoroethylene with polyimide and boron nitride

Polytetrafluoroethylene (PTFE) blended with polyimide (PI) and filled with boron nitride (BN) is prepared through cold pressing and sintering for composites with remarkable wear resistance and reduced coefficient of friction (COF). The characterizations show that BN and PI at different levels, improve the hardness, dynamic thermo-mechanical modulus, thermal conductivity, and tribological properties of PTFE. PI boosts the dispersion and bonding of BN in PTFE. In dry sliding friction of a block-on-ring tribometer, the wear rate and COF of 10:10:80 BN/PI/PTFE reduce to almost 1/300 and 80% of those of pure PTFE, respectively, as the wear mechanism transition from being adhesive to partially abrasive. This occurs only when the additives BN and PI induce a synergistic effect, that is, at concentrations that are not higher than ca. 10 wt% and 15 wt%, respectively. The obvious agglomeration at high percentages of added PI and severe conditions (400 N and 400 rpm) induce strong adhesive failure. The variations in the tensile properties, hardness, crystallization, and microstructure of the composites correspond to different effects. The multiple parameters of the plots of wear and friction are transformed into their contour curves. The mechanism transition maps aid in understanding the influence of various test conditions and composite compositions on the contact surfaces in the space-time framework of wear.

Curvature of real and illusory contours across the blind spot and artificial gaps

Curvature of real and illusory contours across the blind spot and artificial gaps

Morpho-chronology of monogenetic scoria cones from their level contour curves. Applications to the Chichinautzin monogenetic field, Central Mexico

The genesis, distribution and hazards associated with monogenetic volcanic fields pose particular difficulties derived from their dispersed character. Establishing a relationship between the spatial and the age distributions of volcanic cones is necessary both to understand the nature of monogenetic field formation and evolution and to set supported hazard-assessment criteria. We present here a new method –specifically developed to quantify the degree of age-dependent erosion of individual scoria cones– aimed to estimate the relative ages of undated scoria cones in a monogenetic volcanic field from a contour level morphometric analysis of the field digital elevation model (DEM). This method is based on the hypothesis that age and the degree and type of erosion causing significant morphological changes on scoria cones are markedly correlated. It is assumed that, at the time of their formation, monogenetic volcanoes have diverse, yet smooth shapes, which mechanical processes of wearing gradually change in different spatial scales. This evolution is largely evidenced both as changes of the volcano slopes and as height-dependent undulations of the cone surface generated by the hydrometeorological ablation in the otherwise uniform elevation contour lines. Here, we characterize the time-dependence of the shape and size of the altitude isoline undulations by means of the Elliptical Fourier Descriptor spectra of the contour curves of volcanic cones. To test the effects of the DEM data type and resolution on this morpho-chronological dating, we analyze the correlations of published radiometric ages of cones with two datasets of contour curves from the Sierra Chichinautzin monogenetic volcanic field in Central Mexico (SCVF): one obtained from airborne LIDAR surveys (INEGI, Mexico) and the other from a satellite radar mission (DLR, Germany).

Digital laser speckle technique for generating deflection, slope, and curvature contours of bent plates

A digital method is proposed whereby spatial speckles created when an optically rough surface is illuminated by a diffuse coherent laser beam are used to generate slope contour fringes. This is done by photographing the speckles contained in a parallel plane in front of the plate before and after deformation. The resulting photographs are then fast Fourier transformed twice and numerically compared with the digital speckle correlation software called computer-aided speckle interferometry to produce slope contours of the plate. The slope contour data are then stored in a computational array. The curvature contours are generated by numerical differentiation of the slope data; similarly, the deflection contours are generated by numerical integration of the slope data. The curvature data can then be further used in conjunction with plate theory to obtain the bending and twisting moments the plates experience as well as the stress distribution in the surface of the plate. The method is simple and straight forward. A comparison with several other techniques is presented.

Active contour modal based on density-oriented BIRCH clustering method for medical image segmentation

Currently, medical image segmentation has attracted more attention from researchers, which can assist in medical diagnosis. However, in the process of traditional medical image segmentation, it is sensitive to the initial contour and noise, which is difficult to deal with the weak edge image, complex iterative process. In this paper, we propose a new medical image segmentation method, which adopts density-oriented BIRCH (balanced iterative reducing and clustering using hierarchies) clustering method to modify active contour model and improve the robustness of noise. The BIRCH is a multi-stage clustering method using clustering feature tree. The improved model can effectively deal with the gray non-uniformity of real medical images. And we also introduce a new energy function in active contour model to make the contour curve approach to the edge, and finally stay at the edge of the image to complete the object segmentation. Experimental results show that this new model can overcome the influence of complex background on medical image segmentation and improve the speed and accuracy of medical segmentation results.

Robust A*-Search Image Segmentation Algorithm for Mine-like Objects Segmentation in SONAR Images

This paper addresses a sonar image segmentation method employing a Robust A*-Search Image Segmentation (RASIS) algorithm. RASIS is applied on Mine-Like Objects (MLO) in sonar images, where an object is defined by highlight and shadow regions, i.e. regions of high and low pixel intensities in a side-scan sonar image. RASIS uses a modified A*-Search method, which is usually used in mobile robotics for finding the shortest path where the environment map is predefined, and the start/goal locations are known. RASIS algorithm represents the image segmentation problem as a path-finding problem. Main modification concerning the original A*-Search is in the cost function that takes pixel intensities and contour curvature in order to navigate the 2D segmentation contour. The proposed method is implemented in Matlab and tested on real MLO images. MLO image dataset consist of 70 MLO images with manta mine present, and 70 MLO images with cylinder mine present. Segmentation success rate is obtained by comparing the ground truth data given by the human technician who is detecting MLOs. Measured overall success rate (highlight and shadow regions) is 91% for manta mines and 81% for cylinder mines.

Curvature interpretation of gravity data for delineating structural features across the transition zone of Narmada–Son lineament in central India

Potential-field anomalies can be converted to a common function which describes the ridge, peaks over an isolated source. In this study, attempt has been made to interpret curvature attributes of equipotential surface using gravity gradients for delineating thrust–fault locations in one of the seismically active transition zones of Narmada–Son Lineament (NSL) in central India. The NSL is oriented in the ENE–WSW direction, divides the area into two geological provinces. The northern part of this NSL comprises Vindhyan formations and southern part covers Gondwana formations. It has been observed that, the northern part (around Jukehi) of the area has higher elevation with lower gravity anomaly and the southern part (around Khamaria and Kataria) has lower elevation with higher gravity anomaly. The tectonic activities like intrusions, volcanisms and earthquake occurrences were the sources of crustal resettlement during the past in this area. Various researchers commented about the structural configuration; however, the present study helps to understand the structural features using various curvature analysis like maximum, minimum, most-positive, most-negative, mean, dip (profile), strike (tangential), contour (plan), curvedness, shape index and Gaussian curvatures. Out of these curvatures most positive, maximum, mean, dip and curvedness show more effective results compared to other curvatures. However, shape index states domes, ridge, flat, valley, bowl shape type structures. The results are also correlated with the conventional horizontal gravity gradient, analytic signal and tilt derivative analysis. The colour contrast variation of these differential curvatures make in-depth understanding with extensive multiplicities of integrity for delineating subsurface structures.

Development of pasteurized coffee-flavored dairy beverage added with mint extract (Mentha x piperita)

The aim of this work was to evaluate different concentrations of ethanol on antioxidant (phenolic and flavonoid) compounds extraction of Mentha x Piperita aiming at applying the extract in whey-based dairy beverages. The extracts were obtained by cold maceration using water and ethanol as solvents. The extract using water and 70% ethanol had a 13.83 (w w-1) yield, 61.72 mg GAE g-1 phenolic compounds extract, 37.27 mg QE g-1 flavonoid content extract and 0.056 mg mL-1 antioxidant activities. The dairy beverage formulations followed a 22 factorial design in order to evaluate the effect of whey/milk and starch addition on the physical-chemical (pH, acidity, moisture, ash, fat, protein, viscosity, and color) and sensorial characteristics (acceptability) of the product. Analysis of variance (ANOVA) allowed for the development and validation of mathematical models for ash content, lipids, viscosity, and luminosity of the dairy beverage. The effects of whey/milk and starch variables on such characteristics were analyzed by the elaboration of contour curves. The product presented a lower color intensity at the highest whey concentration (75%). The product had a good sensory acceptance, and the 50 whey and 50% milk formulation presented a 7.16 points average and 79.51% acceptance index, suggesting that 50% of whey could be added up to the product’s formulation.

Accurate control of residual stress distribution along the complex surface depth at the root of gears

This study aims to solve the accurate control of residual stress distribution along the depth of complex special-shaped surfaces for providing theoretical basis and experimental support for the research of anti-fatigue manufacturing of key components. Considering the complex profile curve of gear root, a scheme is proposed to predefine the complex curve of tooth root using three types of simple curves, namely, single-segment arc, arc-line combination and multisegment arc by analyzing the characteristics of tooth root shape and curve equation on the basis of meshing theory and gear tooth formation. The corresponding relationship between polishing time and depth under different schemes is calculated on the basis of the principle of electrochemistry and Faraday’s law and compared with the experimental data. On the basis of the complex profile curve of 20CrMnMo standard gear root, the relationship between polishing time and depth calculated using the three schemes is basically similar, and the curve equation is a parabola passing through the origin. The polishing time–depth relationship calculated by the predefined tooth root curve with three tangent arcs has the best agreement with the experimental data compared with the single-segment arc and arc-line combination when the layer-stripping depth is less than 400 µm. The fitting of the experimental data of tooth root polishing shows that a good parabola relationship is found between time and depth. The relationship between the polishing time and depth of tooth root can be calculated by using a simple curve to predefine a complex contour curve. Polishing depth is controlled by accurately controlling polishing time to realise accurate control of the distribution state of tooth root residual stress along the depth. The findings of this study provide theoretical basis and experimental support for future studies on the fatigue performance of key components.

Assessment of surface water and groundwater interaction using hydrogeology, hydrochemical and isotopic constituents in the Imphal river basin, Northeast India

The surface water and groundwater interaction in the Imphal River Basin in Northeast India using hydrogeology, hydrochemical and isotopic constituents has examined to elucidate hydrochemical evolution, surface water and groundwater mixing and recharge condition. Groundwater is characterized by Ca2+–Cl-–HCO3-facies while surface water exhibits Ca2+–Cl- type. Surface water prevailed the intermediate stage of chemical evolution while groundwater characterizes the late stage of chemical evolution. Analysis of flow net combined with hydrogeologic sections revealed significant relationship of surface water and groundwater in the basin. The upper and lower reaches are characterized by contour heads showing an upstream pointing curvature due to depression induced by groundwater discharge where contour lines cross a gaining stream. The middle reach is marked by contour curvature pointing downstream owing to mounding induced by groundwater recharge where it crosses a losing stream. Groundwater shows markedly depleted isotopic composition than surface water. Both surface water and groundwater fall below Global Meteoric Water Line and Local Meteoric Water Line indicating the source of water through infiltration of modern precipitation. The slope of the evaporation line and the original composition of water are identified as 4.92 and −6.58‰ and −42.17‰, respectively. Isotopic d-excess values revealed isotopic composition of semi-arid climate.

Parametric Model for Kitchen Product Based on Cubic T-Bézier Curves with Symmetry

The parametric method of product design is a pivotal and practical technique in computer-aided design and manufacturing (CAD/CAM) and used in many manufacturing sectors. In this paper, we presented a novel parametric method to design a kitchen product in the residential environment, a kitchen cabinet, by using cubic T-Bézier curves with constraints of geometric continuities. First, we introduced a class of cubic T-Bézier curves with two shape parameters and derived the G1 and G2 continuity conditions of the cubic T-Bézier curves. Then, we constructed shape-controlled complex contour curves of the kitchen cabinet by using closed composite cubic T-Bézier curves. The shapes of the contour curves can be adjusted intuitively and predictably by altering the values of the shape parameters. Finally, we studied shape optimization and representation of ellipses for the contour curves of the kitchen cabinet by finding optimal shape parameters and applicable control points respectively. The provided modeling examples showed that our method in this paper can improve the design and scheme adjustment effectively in the conceptual design stage of kitchen products.

Study on Influence of Micro-tool Tip Arc Waviness on Cutting Micro Aspheric Surface

In this paper, the influence of the waviness of tip arc profile on the surface quality of micro transition arc workpiece is studied. Firstly, the contour curve of the surface of the micro tool was measured by using the radius amplitude measuring instrument, and the characteristic parameters of the waviness in the contour curve were found. A simulation study of the effect of feed rate on the quality of the machined surface of a sine wave model with different characteristics was performed by Matlab. It can be known from the simulation results that when a sine wave of 0.05sin(10t) exists in the contour of the tool tip arc, when the feed rate is small, the impact on the surface accuracy of the workpiece is greater, and a sin wave of 0.02sin(30t) locally affects the regional surface roughness is greater. With the increase of feed rate, a sin wave of 0.02sin(30t) has no effect on the surface roughness of the partial area, while a sin wave of 0.05sin(10t) still has a greater effect on the surface roughness of the partial area.

Visualization of coalescence behavior of two bubbles with smoothness constraint

A new method based on 2D contour curve fitting and 3D rotation surface generation to visualize the coalescence phenomenon of two bubbles in static water is presented. First, some contour points are extracted from key frame images in different coalescence stages of two bubbles. Second, those points are fitted using a new approach combining piecewise curve fitting with a smoothing constraint. Third, a family of transition functions is proposed to deal with continuous changes of contour curves in the process of coalescence. Finally, we use those contours to generate dynamical 3D rotation surfaces and achieve the continuous deformation visualization of two-bubble coalescence.

Egg volume estimation based on image processing and computer vision

In chicken egg production line systems, grading based on vision systems is challenging due to ambient light conditions and egg occlusion problems. This study introduces a depth image-based chicken-egg volume estimation system. Two modes of egg configurations on a sorting line were evaluated; single-egg (no occlusion) and multi-eggs (partially occluded, i.e., simple and complex). Contour curvature analysis and k-closest M-circle-center algorithms were used to segment the occluded eggs. Thirteen regression models based on the egg image (single egg) features were trained. The Exponential Gaussian Process Regression outperformed all the explored models with RMSE of 1.175 cm3 and R2 of 0.984. The same model estimated the volume of the eggs under partial occlusion at RMSE of 1.080 and 1.294 cm3 for simple and complex, respectively. This introduced system can be applied as an accurate, consistent, fast, and non-destructive in-line sorting technique of chicken eggs in a production line system.

Factorial design and response surface optimization for modeling photovoltaic module parameters

In this paper, based on factorial design of experiments method (DoE), predictive model and surface response analysis methodology was used for studying, modeling, characterizing and optimizing the parameters of a mono-crystalline photovoltaic (PV) panel behavior considering the interactive effects of two variables surface PV cell temperature and solar irradiation levels. The DoE concept allows finding the predictive model of each parameter behavior that uses the experimental data. It enables accurate predictions of the responses according to input factors variations. This contribution evaluates the output parameters by predicting these mathematical models of the three responses of a mono-crystalline PV panel: the maximum power Pm, the short-circuit current Isc and the open circuit voltage Voc as function of the influences of both input parameter factors: illumination and temperature. In addition, to validate the results of the DoE predictive models, the surface response and the contour curves analysis were used to bring out the optimum of each response in each operating point covering the domain of the study by the use of a script developed under Minitab is deduced. The obtain results are compared with experimental data.

EGSnrc application for IMRT planning.

The aim of this study was to describe a detailed instruction of intensity modulated radiotherapy (IMRT) planning simulation using BEAMnrc-DOSXYZnrc code system (EGSnrc package) and present a new graphical user interface based on MATLAB code (The MathWorks) to combine more than one. 3ddose file which were obtained from the IMRT plan. This study was performed in four phases: the commissioning of Varian Clinac iX6MV, the simulation of IMRT planning in EGSnrc, the creation of in-house VDOSE GUI, and the analysis of the isodose contour and dose volume histogram (DVH) curve from several beam angles. The plan paramaters in sequence and control point files were extracted from the planning data in Tan Tock Seng Hospital Singapore (multileaf collimator (MLC) leaf positions - bank A and bank B, gantry angles, coordinate of isocenters, and MU indexes). VDOSE GUI which was created in this study can display the distribution dose curve in each slice and beam angle. Dose distributions from various MLC settings and beam angles yield different dose distributions even though they used the same number of simulated particles. This was due to the differences in the MLC leaf openings in every field. The value of the relative dose error between the two dose ditributions for "body" was 51.23 %. The Monte Carlo (MC) data was normalized with the maximum dose but the analytical anisotropic algorithm (AAA) data was normalized by the dose in the isocenter. In this study, we have presented a Monte Carlo simulation framework for IMRT dose calculation using DOSXYZnrc source 21. Further studies are needed in conducting IMRT simulations using EGSnrc to minimize the different dose error and dose volume histogram deviation.